railroads are only as strong as the cargo they carry, and that means coal, oil, chemicals and agriculture, all of which are sliding lower.

For years, coal has been in a slow 2% decline, but this year, shipments of coal have plummeted down 8.8%, as 84 of our nation's 681 remaining coal-fired power plants are set to close. The fact is, coal shipments are not coming back.

Then there's oil. With more and more pipelines being built, it's just not economical to ship oil via rail, especially with oil under $50 a barrel. Other cargo, like chemicals, agriculture are also bad.

Only intermodal shipments have any chance of a rebound, Cramer concluded, and that's simply not enough to make these stocks investable.